While Niels Bohr and Werner Heisenberg were meeting in Copenhagen in 1941, the American nuclear bomb program was still in its genesis. Colonel Leslie R. Groves, an Army Corps engineer who had just finished building the Pentagon, took charge of the program -- now called the Manhattan Project -- in September of 1942. Groves quickly hired Dr. J. Robert Oppenheimer, a brilliant physicist, to be the project's scientific director.

Dr. J. Robert Oppenheimer

Because secrecy was of paramount importance, both men knew they needed a central laboratory in some remote location where they could build and test a bomb. In the fall of 1943, Oppenheimer and his team found the perfect site -- a mesa of 7,200 feet above sea level completely isolated from any major city.

The site they chose was Los Alamos, New Mexico.

Construction on cheap barracks-like buildings not meant to outlast the war began almost immediately. Within three years, the Los Alamos Laboratory had designed and was very close to completing two prototype atomic bombs.

Meanwhile, the war in Europe had ground to an end. V-E Day was declared on May 8, 1945, with Germany in ruins and 39million people dead. With the war against Japan still raging in the Pacific, however, the pace at Los Alamos did not let up.

By the summer of 1945 a bomb was ready for testing. A flat and desolate area was chosen 200 miles south of Los Alamos near the Alamogordo Bombing Range. Oppenheimer named the test site "Trinity."

On July 16, 1945, at about 5:30 in the morning, soon after a thunderstorm had swept clean the area, the first nuclear bomb was exploded.

Two scientists working at Los Alamos and present at the Trinity explosion were Frank Oppenheimer -- brother of J. Robert Oppenheimer -- and Robert Wilson.
Frank Oppenheimer was a Berkeley physics Ph.D. trouble shooting the Trinity test for his brother, and Wilson was group leader of the cyclotron program.

In the following videos, Wilson and Oppenheimer recall the moral issues they wrestled with as they helped build the bomb. They also describe what it was like to see the first man-made nuclear explosion in the history of mankind.

Dilemma of Building the Bomb

Remembering the Explosion

Excerpts from THE DAY AFTER TRINITY by Jon Else, courtesy of Pyramid Media.